In October of 2000, the USS Cole was steaming alone off the Horn of Africa and was critically low on fuel. Since there was not a replenishment ship in the Gulf of Aden region, the Cole was directed by the US Navy's Fifth Fleet to make a brief stop for fuel in the Yemen port of Aden.

Shortly after mooring, a small zodiac approached the ship on the port side. Without warning there was an explosion amidships. The boat laden with over 220 kilograms of explosives had rammed the ship, ripping a 12-metre-square gash in the ship, killing 17 sailors and injuring dozens.

The crew of the Cole fought for the next 96 hours to keep the ship afloat. How could this possibly happen after the United States lost 241 service members in the Beirut Barracks bombing in 1983, and 19 service members in the Khobar Towers incident in Saudi Arabia in 1996? Did the US fail to read the lessons or were there flawed rules of engagement to defend its forces?

The US Department of Defense's report on the Cole incident found that the Department had made significant progress in the protection of US forces for installations, but the attack on the Cole "demonstrated a seam in the fabric of efforts to protect our forces, namely in-transit forces".

It was clear from the lessons learnt that US naval commanders and their crews were not prepared to face asymmetric threats of modern warfare. Today's warfare is far different from the Cold War days.

There is also the challenge to determine who the enemy is and where it will attack next. The leadership of US forces operating under the Fifth Fleet's command had determined that the port of Aden was safe enough for a quick refuelling stop for the Cole, but terrorists saw it as an opportunity to attack a US ship in a foreign port where security measures were almost nonexistent and the ship would most probably not be prepared for a fast-moving suicide boat attack.

The terrorists were right and the US Navy needed to take back the home-field advantage from terrorist groups, and with the growing threat of swarm attacks in the Arabian Gulf the navy needed to move fast.

The one finding of the report that stood out was that the standing rules of engagement for US forces were adequate against a terrorist threat. Those rules never limit commanders' inherent right of self-defence and their obligation to use all necessary means available and to take the appropriate action in self-defence of the commander's unit and other US forces in the vicinity.

The question that naval commanders face every day in the operational environment is whether an approaching vessel is another fishing boat or a terrorist attack. In that same scenario on July 16, the apparent misidentification and lack of communication of the intentions of a UAE fishing boat led to the US Navy oil-supply ship USNS Rappahannock firing on the boat, tragically killing one fisherman and wounding three others.

When operating at sea or entering port, it is not uncommon for naval ships to be approached by pleasure craft and fishing boats. Ships operating in the Arabian Gulf will often find their radar scopes cluttered with countless surface contacts.

Yes, they may look like harmless fishing vessels, but the naval commander must remain vigilant and prepare his crew for a possible change of events that could suddenly see a fishing boat take off at high speed towards his unit.

In the case of the Cole, the terrorists actually waved to the security watch moments before they rammed the ship. For the commander in modern warfare it is important to be able to instantly determine a hostile act or demonstrated hostile intent.

As a result of the Cole attack, US law was enacted to provide a "naval vessel protection zone", forbidding unidentified vessels from approaching within 100 metres of a US Navy ship and requiring vessels operating within 500 metres to travel at minimum speed. These are the minimum standards for protection against attack. Each commander must find their comfort zone for when he first issues verbal warnings for the approaching vessel or vessels to stand clear.

If it is determined that the approaching threat is not abiding by the verbal warnings, the commander must be prepared to fire warning shots. Warning shots are employed in most cases to warn a vessel to stand clear of the unit firing or risk being hit by disabling fire.

As a result of the Cole attack and the asymmetric threat in the Arabian Gulf, it is a standard warning today that mariners are strongly advised to remain clear of all US Navy and coalition warships and to identify themselves and make their intentions known when operating in the vicinity of such forces.

If queried, mariners should make their intentions known and, if given directions by coalition forces, they should promptly execute those orders without delay. Mariners are constantly reminded that coalition warships are prepared to take whatever measures necessary, including the use of deadly force, against any contact that demonstrates a hostile act or hostile intention. The use of deadly force will only be used in situations of extreme necessity and as a last resort.

The coalition forces operating within the Fifth Fleet area of responsibility have demonstrated that they are determined to ensure the safe navigation of all vessels in the coastal waters and on the high seas. However, these forces are prepared to take all necessary actions to protect their property and ensure the safety of US service members.

Rear Admiral Terry McKnight (Ret)was the first commander of Combined Task Force 151 for counter-piracy operations in the Gulf of Aden. His book Pirate Alley: Commanding Combined Task Force 151 on the Hunt for Somali Pirates, will be published in October